Another thing to remember is that the F16 needs a mast with a different profile to the A class for 2 reasons

1, We have to keep it up when the kite is up - thus it must be stronger than an A class mast.
2, As wouter says, we also sail 2 up - thus we need a stiffer mast. (unless you optimise for single handed)

Now, during my investigations on this I can report that you could build a very light mast but it would not be stiff enough to drive the boat properly - it would not break, but it would not be STIFF enough to be the right shape.